Wave Energy: Riding the Oceans for Clean Power

Introduction

A lot of us have already heard of the most popular renewable energy sources, for example solar or wind power.

But did you believe that renewable energy can also be generated from other natural resources and phenomena, like the movement of waves?

Wave energy is one more form of renewable energy that may be utilised as an alternative to traditional energy sources such as fossil fuels, which are finite resources that produce harmful carbon emissions into the atmosphere when used for energy.

What is Wave Energy & its uses?

Wave energy is a type of energy generated by the ocean or sea waves. It is also known as ocean energy as well as sea wave energy. The severe vertical motion of surface ocean waves includes an enormous amount of kinetic (motion) energy, which wave energy devices capture and employ to perform useful activities.

The wave energy generated is utilised for a variety of practical tasks, including producing electricity, water desalination, and reservoir pumping.

History of wave energy

The attempt of wave energy is going returned to 1799, while Girard and his sons carried out for a patent to apply wave energy in Paris. Yoshio Masuda, a former Japanese navy commander, and considered as the inventor of contemporary wave energy technology, pioneered the modern pursuit of wave energy in the Imperial Japanese Empire in 1940.

After the 1963 oil crisis, Professor Stephen Hugh Salter created the eponymous Salter duck wave energy device, which was capable of converting 90% of wave motion into electricity with an efficiency of 80%.

Several other first-generation devices were tested in the 1980s, but when oil prices fell, wave-energy funding decreased. Later, climate change re-energized the field.

In 2003, Orkney, Scotland, created the world’s first wave energy test facility to begin the development of a wave and tidal energy industry. More wave and tidal energy devices have been deployed thanks to the European Marine Energy Centre (EMEC) than any other single place. Following its foundation, test facilities sprung up in a variety of different nations across the world, providing services and infrastructure for device testing.

Despite a UK government investment of over £200 million over 15 years, Strathclyde University and Imperial College conducted a 2017 research that focused on the failure of developing “market ready” wave energy devices.

During the 2010s, public agencies continued and in several countries increased funding for wave energy research and development. This includes the EU, the United States, and the United Kingdom, whose yearly allocations have historically ranged between $5 and $50 million USD. This, in conjunction with private funding, has resulted in a huge number of current wave energy projects.

How does wave energy work?

The waves and tides have significant energy potential that may be harnessed. Scientists, companies, and national governments have not yet to figure out how to make it a viable product.

Wave power is generated by the up-and-down motion of floating devices put on the ocean’s surface.

In other words, wind causes waves, and waves cause energy.

High-tech equipment catches the natural motions of ocean currents and swells as they travel across the ocean to create power.

Wave energy devices

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Ocean wave energy has several advantages over ocean wind energy, including being more predictable, less variable, and offering a higher accessible power density. Wave energy systems are classified as shoreline, nearshore, or offshore based on the distance between the energy conversion device and the shoreline. So, how do these three types of energy harvesting technologies differ?

  • The shoreline devices

Shoreline devices are land-attached or implanted wave energy devices that allow operation both in and out of the water.

  • Nearshore devices

Nearshore devices are characterized by using wave energy that originates directly from the breaker zone and the waters immediately behind the breaker zone (at 20 m water depth).

  • Offshore devices (deep water devices) 

Offshore devices are furthest offshore and reach beyond breaker lines, taking advantage of the high energy densities and higher power wave profiles found in deep ocean waves and surges. An advantage of offshore devices is that they do not require significant coastal earthworks, as is the case with onshore devices.

Because most of the energy in a wave is concentrated at the surface and decreases rapidly with depth. There is a surprising variety of designs that increase the energy available for capture.

Primary types of wave energy conversion

  • Point absorber

 

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These are tiny vertical devices that collect energy from waves from all directions and are attached directly to the seabed or tethered by a chain. The rocking or pitching motion of a floating device generates electricity in these devices.

Floating buoys, floating bags, ducks, and articulated rafts are examples of common wave energy devices. In a variety of devices, these devices convert the up and down motion of waves into rotational or oscillating motion to generate electricity.Floating devices have the advantage of being able to be placed in deeper water, where wave energy is higher.

  • Wave attenuator (linear absorbers)

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Long, horizontal, half-submerged serpentine devices arranged parallel to the wave direction are called “linear absorbers”. A wave attenuator consists of a series of cylindrical parts connected by flexible hinged joints that allow the individual sections to twist and rotate relative to each other.

The device’s wave-induced motion is used to pressurize a hydraulic piston, called a ram, which pumps high-pressure oil through smoothing accumulators to drive a hydraulic turbine generator that produces electricity. The oscillating movement of a shaft is then converted into hydraulic pressure by shaft attenuator.

  • Overtopping devices

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Fixed or floating structures with ramps and tapering sides perpendicular to the waves are referred to as “spillover” devices. Sea waves are driven up the ramp and over the sides, filling a tiny tidal reservoir 2-3 meters above sea level. The potential energy of the water trapped in the reservoir is then recovered by returning the water to the sea using a low-head Kaplan turbine generator to generate electricity. The potential energy present in the water column is then converted into mechanical energy by overtopping devices.

  • Oscillating Water Column

        

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The Oscillating Water Column (OWC) is a wave energy converter that uses the movement of waves to compress and decompress air in a partially submerged chamber attached to the shoreline. This action drives a turbine that generates electricity. The OWC can be constructed using natural caves or man-made chambers and is typically placed perpendicular to the waves to maximize energy capture.

Wave Energy Advantages 

  • Renewable

Wave energy is a renewable energy source produced by the movement of waves caused by wind. Wind will always exist as long as the sun is shining, making wave energy a renewable & sustainable source of energy. Wave energy, unlike fossil fuels, is not finite & will not deplete soon.

  • Environment Friendly

Wave energy is a very efficient energy source. This is due to the fact that waves are almost constantly in motion. Despite ebbs and tides, the average motion stays constant. As a result, energy may be continually harnessed. It is true that the quantity of energy produced and transferred by waves changes from season to season and year to year. However, the production of energy is continuous.

  • Vast Amounts of Energy can be Produced

The amount of power that the waves may generate is just immense. It is so massive that the power density along the beach is around 30kW to 40kW per metre of a wave. As we progress deeper into the water, the power density rises to around 100kW. It is extremely massive.

  • Small Footprint

A wave power plant less than half a square mile in size would produce more than 30 MW of wave energy, enough to power about 20,000 US households.

  • Size advantage

Wave energy devices may be adjusted to handle electricity demand and hence created in a variety of sizes appropriate for each site. In contrast, the production of electricity from fossil fuels often needs huge facilities.

  • Efficient Energy Production

The energy density of waves at shorelines is typically 30-40 kW/m of wave, while most waves can produce 100 kW/meter of electricity further out into the ocean. Less than ½ mile2 of water has the capacity to produce more than 30 MW of power, enough to supply power to 20,000 British houses.

  • Low Operational Cost and Fewer Maintenance Issues

When we put wave energy facilities online, the vast majority of them will be self-sustaining. That means no fuel expenses, fewer transportation impacts, as well as less maintenance to deal with when using wave power and energy. If the initial cost is affordable, the long-term benefits of this technology can make it a worthwhile experience for everyone.

Wave Energy Disadvantages

  • Suitable to Certain Locations

The chief disadvantage of capturing your energy from the waves is location. Just power plants and cities near the sea will immediately benefit from it. Wave energy is not a feasible source of power for everyone due to its source. Wave energy isn’t the clean energy solution for everyone since landlocked areas   and towns distant from the sea must find additional sources of electricity.

  • Effect on Marine Ecosystem

Even while wave energy is clean, it still makes hazards to some of the beings who live near it. For gathering energy from the waves, large devices need to be placed near and in the sea. The devices disturb the bottom, alter the habitat of near-shore species (such as crabs and starfish), and generate noise that disturbs sea life. There is also a risk that harmful chemicals utilised on wave energy platforms would spill and pollute the water surrounding them.

  • Source of Disturbance for Private and Commercial Vessels

Because wave energy plants must be located near the shoreline and populous regions, they may disrupt commercial, private vessels and the beachgoers. As a result, both governments and companies have to assess the needs of individuals who may be harmed by these plants while simultaneously evaluating their advantages.

  • Wavelength

Wind power is strongly influenced by wavelength, wave speed, and water density. To produce a significant amount of wave power, they need a consistent flow of powerful waves. Some places have unstable wave behaviour, making it difficult to estimate correct wave power and, as a result, cannot be regarded as a reliable energy source.

  • Slow Technology Improvements

Wave energy has been evolving since the 1700s, but it is still a fledgling technology that needs more development. This sluggish development is a barrier to investment in renewable energy.

  • High Costs

Wave energy generation offers many benefits, but it also has substantial drawbacks, such as costly construction, maintenance, & repair expenses. The unpredictability as well as the sometimes strength of the waves might damage the equipment, increasing the costs. As a result, while assessing the viability of wave energy production, considerable attention is required.

  • Weak Performance in Rough Weather

During bad weather, wave power performance decreases greatly. They must be able to tolerate bad weather.

Wave Energy Presence

Asia and Australia have the greatest amount of wave energy. It is also found in both South as well as North America. Despite their small size, Western and Northern Europe contain considerable quantities of energy. Because of their mid-latitude location, Central America, the Mediterranean Sea, and the Atlantic Archipelagos suffer greatly.

Wave energy, tidal energy, ocean current energy, salinity gradient energy, and ocean thermal gradient energy are only a few of the renewable energy sources formed by ocean water motion that may all be utilised to generate electricity.

What makes wave energy a renewable energy source?

Wave energy, similar to solar, wind, and geothermal energy, is a renewable source. Waves will continue to be a feasible source of kinetic energy as long as the Earth continues to orbit the sun and the moon continues to orbit the Earth. Wave energy also emits fewer carbon emissions than traditional fossil fuels such as coal or oil, making it a more environmentally friendly choice.

Top wave energy convertor companies

CorPower Ocean

CorPower Ocean is a Swedish wave energy company which has created a compact & powerful wave energy converter. It has designed a point absorber with a heaving buoy on the surface that absorbs energy from the combined surge & heavy motion of the waves.

Ocean Power Technologies

Ocean Power Technologies is a wave energy company based in the USA that has created a variety of wave energy converters. This company provides a ‘PB3 powerbuoy,’ which gives continuous power to on-board payloads, a ‘Hybrid powerbuoy,’ that offers offshore power as well as communications, and a ‘Subsea battery,’ which is used to power subsea payloads.

Wello Oy

Wello Oy is a Finnish wave energy company which has created the Penguin, a special wave energy converter. The Penguin is a floating device which converts the energy of ocean waves into electricity.

Conclusion

Wave energy is a renewable energy source that can be generated from the movement of ocean or sea waves and can be used for producing electricity, water desalination, and reservoir pumping. The history of wave energy dates back to 1799, and modern wave energy technology was pioneered in 1940. Wave energy systems are categorized as shoreline, nearshore, or offshore devices.

Wave energy system has many advantages such as Renewable, Environment Friendly, Small Footprint,  and  Efficient Energy Production,  However; wave energy has some disadvantages, including its location dependence, impact on marine ecosystems, disturbance to private and commercial vessels, wavelength dependence, slow technology improvements, high costs, and weak performance in rough weather.

Wave energy is found in Asia, Australia, South and North America, Western and Northern Europe, while Central America, the Mediterranean Sea, and the Atlantic Archipelagos have less of it due to their mid-latitude location.

References

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